Blender Git Loki

Applying patch by Fredrik Hansson: Extra blend modes.

Actually should be called the blend mode imperialism commit, this commit
adds no more no less about 15 new blend modes.

The catch is that the float versions will probably have to work in
display colour spaces, but seeing how the rest of the blending code is I
think this can go in right now.

Thanks to Fredrik for the original patch and to Campbell for writing
uncrustify. A solid weapon in the war against the non-blender-style-

To painters out there: Test this extensively!